Apple and Google did not initially confirm the report. But a document posted online by Apple shows that the Cupertino, Calif.-based company does use Google Cloud Platform for meeting part of the requirements of iCloud storage. The iCloud service provides backups to data on devices including iPhones, iPads and Macs.

The online document, Apple's iOS Security guide, discloses that Apple uses both Google Cloud Platform and AWS for iCloud. CNBC reported that the previous version of the document had mentioned Microsoft Azure as one of the services used for iCloud, instead of Google Cloud Platform.

Sources previously told CRN that Apple was cutting back on its use of AWS and relying more on Google Cloud Platform.

Michael Oh, CTO of Cambridge, Mass.-based solution provider TSP, said it's notable that Apple is choosing to depend on the major cloud players rather than setting up its own cloud infrastructure for iCloud and other services -- even though that means giving business to competitors. Apple's iPhone, for instance, competes fiercely with smartphones running Google's Android operating system.

"Presumably, Apple has the resources to do [data centers] themselves. The fact that they're leveraging others is probably a good thing," Oh said. "I remember when iCloud had a lot of criticism -- downtime and ongoing issues -- but it's been awhile since I've heard those types of criticisms. Presumably it's because they're using the same infrastructure everyone else relies on."

Apple could build their own data centers, Oh said, "but that would be on top of the retail stores and all their other infrastructure and manufacturing. The fact is, what are they going to gain from it?"

Oh said that Apple's moves also bode well for Google Cloud Platform, which trails AWS and Azure in terms of market share but has grown to generate more than $1 billion per quarter for parent company Alphabet Inc. "Clearly, they're doing something right to gain the trust of a company like Apple," Oh said.

Earlier in February, Google CEO Sundar Pichai said he believes the Google Cloud Platform is the world's fastest-growing public cloud provider.

"Google Cloud Platform and G-Suite have reached meaningful scale. … The number of [customer] deals worth over a million dollars across all cloud products have more than tripled from 2016 to 2017," Pichai said during Alphabet's fourth-quarter earnings call.